Signature stacking machine

ABSTRACT

A receiver is adapted to support an aligned stack of signatures. First and second adjacent conveyors are adapted to transport between them a stream of signatures moving edgewise such that the stream approaches one end of the stack in a direction transverse to its length. A stop is disposed along the backside of the stack transverse to the stream. The conveyors are bowed in cross section toward the stack at a point short of the front side of the stack so the signatures are stiffened before they reach the stack. The conveyors are partially wrapped around a direction changing rotatable drum the radius of which is the same order of magnitude or larger than the length of a signature. The outer conveyor wrapped around the drum is an endless belt arrangement mounted on three rotatable supports. The two supports between which the belt arrangement is wrapped around the drum are translationally fixed and the remaining support is movable transverse to its axis of rotation to permit the length of belt between the first two supports to change responsive to changes in the thickness of the sheets. One of the conveyors extends across the end of the stack and stops short of the backside of the stack so the second conveyor gradually moves out of contact with each sheet in turn as it moves into alignment in the stack. The receiver is a horizontal platform on which the stack lies in horizontal alignment. Two elongated independently movable rotatable vertical members are located at the other end of the stack from the conveyors. These members are loaded such that they are urged against the other end of the stack. The signatures are periodically marked in synchronism with the movement of the conveyors to produce along the length of the stack an indication of the number of sheets in the stack.

v United States Patent Appl Filed Inventor Patented Assignee Edmund T. H. Schmidt Woodland Hills, Calif.

Oct. 28, 1968 July 6, 1971 Timer Mirror Company Los Angeles, Calif.

16 Claims, 4 Drawing Figs.

rm. Cl Field of Search US. Cl

, Reierences Cited UNITED STATES PATENTS Primary Examiner-Joseph Wegbreit Attorney-Christie, Parker and Hale SIGNATURE STACKING MACHINE ABSTRACT: A receiver is adapted to support an aligned stack of signatures. First and second adjacent conveyors are adapted to transport between them a stream of signatures moving edgewise such that the stream approaches one end of the stack in a direction transverse to its length. A stop is disposed along the backside of the stack transverse to the stream. The conveyors are bowed in cross section toward the stack at a point short of the front side of the stack so the signatures are stiffened before they reach the stack. The conveyors are partially wrapped around a direction changing rotatable drum the radius of which is the same order of magnitude or larger than the length of a signature. The outer conveyor wrapped around the drum is an endless belt arrangement mounted on three rotatable supports. The two supports between which the belt arrangement is wrapped around the drum are translationally fixed and the remaining support is movable transverse to its axis of rotation to pennit the length of belt between the first two supports to change responsive to changes in the thickness of the sheets. One of the conveyors extends across the end of the stack and stops short of the backside of the stack so the second conveyor gradually moves out of contact with each sheet in turn as it moves into alignment in the stack. The receiver is a horizontal platform on which the stack lies in horizontal alignment. Two elongated independently movable rotatable vertical members are located at the other end of the stack from the conveyors. These members are loaded such that they are urged against the other end of the stack. The signatures are periodically marked in synchronism with the movement of the conveyors to produce along the length of the stack an indication of the number of SIGNATURE STACKHNG MACHINE BACKGROUND OF THE INVENTION This invention relates to the handling of flexible sheets, such as signatures from a printing press, that are moving in an edgewise overlapping stream and, more particularly, to a machine for arranging such flexible sheets in an aligned stack.

A. R. Stobb, U.S. Pat. 2,884,243, issued Apr. 18, 1959, discloses a signature stacking machine including a horizontal platform for receiving and supporting a horizontally aligned stack of signatures and first and second adjacent conveyors adapted to transport to the platform a stream of overlapping signatures moving edgewise off a printing press. A transverse stop is disposed along the backside of the aligned stack in the path of the signature stream. The first conveyor extends to a point short of the front side of the stack, and the second conveyor extends completely across one end of the stack to a point well beyond the backside. As the stream is transported between the conveyors, it approaches the one end of the stack in a direction transverse to its length. Each signature in turn is pushed against the stop into alignment in the stack by the second conveyor. As the second conveyor moves across the front of the stack, it passes over a straight support, i.e., pulley shaft, upon which the first conveyor is mounted and thereafter begins to bow gradually in cross section as it extends across the end of the stack, to stiffen the signatures before they reach the stop. The conveyors are partially wrapped around a rotatable drum to change their movement from a horizontal direction as the signature stream leaves the press to a vertical direction as the stream approaches the stack. The drum has a radius that is less than one-half the length of the signatures.

Although the Stobb machine greatly reduces the human effort required to stack signatures, it is somewhat limited in the type of signature streams it is capable of handling. For example, the Stobb machine often handles well signatures fed to it from a printing press with the folded edge trailing but tends to mutilate the same signatures when they are fed to it with the folded edge leading. Specifically, when the folded edges of the signatures are leading, the second conveyor tends to peel the unfolded edge of the sheets of a signature up toward the folded edge after the folded edge abuts the stop, thereby ripping the signature apart and possibly disabling the machine. Further, thick signatures produce difficulty because the severe bend introduced into the signatures as the stream passes over the direction changing drum may destroy the pin hole connection of the sheets of the signatures. As a result of the small radius of curvature of the conveyors as they pass over the drum, the difference in tangential velocity of the conveyors increases sharply as the thickness of the signatures increases, thereby causing slippage between the outer conveyor and the stream. To minimize this effect, intricate apparatus must be provided to make adjustments in the speed of the outer conveyor as different signature thicknesses are handled.

Difficulties are also encountered in unloading the machine, i.e., removing part of the stack from the'platform. A heavy vertical slab on the platform holds the stack in place. As signatures from the stream are added to the stack, the stack moves away from the conveyors, pushing the slab along the platform in front of it. To remove part of the stack from the platform, the person operating the machine slides the slab away, lifts out a group of signatures, and then slides the slab back against the new end of the stack on the platform. While the slab is away from the new end of the stack, the operator must support it with his hand, which is very inconvenient. ln addition, the operator must estimate the number of signatures he is unloading by the length of the stack. This demands the continuous attention of the operator and is also rather imprecise because air is trapped between the sheets of the signature, thereby causing the number of signatures in a given stack length to vary significantly.

SUMMARY OF THE INVENTION The invention concerns improvements that increase the versatility of a signature stacking machine to handle different types of signature streams without adjustments and that facilitate the removal of part of a signature stack from the machine in the course of its operation.

In one aspect of the invention the first and second conveyors are bowed in cross section toward the stack at a point short of the front side of the stack to stiffen the signatures in the stream before they reach the stack. Specifically, the support for the first conveyor over which the second conveyor passes as it crosses the end of the stack is V-shaped, thus forcing the first and second conveyors to bow in cross section as they approach the stack. By bowing the conveyors before the signatures reach the stack rather than after the signatures start across the stack, each signature is bowed along its entire length and a greater extent of bowing can be introduced. Thus the signatures tend more to remain intact as they slide across the end of the stack, and they are stiffened more when they abut against the stop. As a result, mutilation of the signatures as they are aligned is discouraged.

According to another aspect of the invention, the signatures are further protected against mutilation as they are aligned by extending the second conveyor across only a portion of the end of the stack to a point short of the backside of the stack. Thus, the second conveyor gradually moves out of contact with each sheet in turn as it moves into alignment in the stack. Preferably, the second conveyor stops short of the backside of the stack by the amount of offset of the signatures in the overlapping stream so the force of the second conveyor on each signature is released at the time such signature moves into alignment in the stack.

Another aspect of the invention calls for a direction changing drum that has a radius the same order of magnitude or larger than the length of the signatures being handled. As a result, signatures having different thicknesses can be handled without requiring a readjustment of the speed of the outer conveyor, the signatures tend to remain intact as they are bent around the drum, and most of the air is removed from between the sheets of the signatures so they may be arrangedmore compactly in the stack.

In another aspect of the invention, the outer conveyor wrapped around the drum is an endless belt arrangement mounted on at least three spaced apart rotatable supports. The two supports between which the belt passes across the drawn are translationally fixed and the remaining support is movable transverse to its axis of rotation to pennit the length of belt between the first two supports to change responsive to changes in the thickness of the signatures. This improvement also serves to obviate adjustments of the machine to handle signatures having different thicknesses.

To facilitate the removal of part of the signature stack from the machine, a pair of independently movable, elongated vertical members are located at the other end of the stack from the conveyors. The vertical members are independently loaded so they are urged against the other end of the stack as the stack moves away from the conveyors. A convenient number of signatures, called a lift, is removed from the end of the stack by pulling it horizontally in a direction transverse to the length of the stack. As a lift is removed, it rolls along the vertical members, which immediately move against the new end of the stack that is formed. Since the vertical members move independently of one another, they provide firm support to the stack on the platform despite differences that may develop in the length of the stack on the front and backsides. The signatures are periodically marked in synchronism with the conveyors to produce along the length of the stack an accurate indication of the number of sheets in the stack. By removing from the machine those signatures lying between a given number of marks, uniformity is achieved in the number of signatures in each lift without particular attention on the part of the operator.

, 3 BRIEF DESCRIPTION OF THE DRAWINGS with the signatures removed;

FIG. 3 is a partial back oblique view of the machine of FIG. 1 in section; and

FIG. 4 is a partial back elevation view of the machine showing one of the vertical posts.

DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT In the drawings, a conveyor 1 carries an overlapping,

v horizontal stream 2 of signatures from a printing press, not

shown. Conveyor 1 rotates in a clockwise direction, transporting stream 2 from left to right as viewed in FIG. 1. The top surface of each signature in stream 2 overlaps the bottom surface of the following signature. In the following description, consistency is maintained in the use of the terminology top surface" and bottom surface of the signatures even when these surfaces become vertically oriented. For the purpose of discussion, it is assumed that the leading edge of each signature is folded and the trailing edge of each signature is unfolded, i.e., comprises the 'ends of the sheets of the signature. The components of the signature stacking machine are mounted on a frame 3 having a base 4. A receiver 5, which is adapted to support an aligned horizontal stack 6 of signatures, is located at the top of frame 3.

In this specification, the length of stack 6 is taken to mean the horizontal dimension transverse to the large flat surfaces of the signatures; the front side of stack 6 is taken to mean the horizontal bottom surface of stack 6 formed by the unfolded edges of the signatures; the backside of stack 6 is taken to mean the horizontal top surface of stack 6 formed by the folded edges of the signatures; and the ends of stack 6 are taken to mean the large flat vertical surfaces of the signatures located on either end of stack 6.

Conveyor 1 comprises a plurality of endless belts arranged side-by-side. The belts of conveyor 1 are mounted between a rotatable drum 7 and another rotatable drum (not shown in FIG. 1), which is driven by the printing press. As a result, the translational speed of conveyor 1 is synchronized to the operation of the printing press. Drum 7 is mounted on a shaft 8 that is rotatably supported by frame 3. Conveyors 10 and l 1, each of which also comprises a plurality of endless belts arranged side-by-side, are disposed adjacent to one another between conveyor 1 and receiver 5 to transport stream 2 therebetween. Conveyor 11 is mounted on pulleys 12, pulleys 13, and a rotatable drum 14. Drum 14 is mounted on a shaft 21 that is rotatably supported by frame 3. Pulleys 12 and 13 are rotatably mounted on frame 3. A pair of obliquely oriented supporting beams 15 are attached to either side of frame 3. Pulleys 13 are mounted on frame 3 by a rod 16 that is suspended between beams 15. A large drum 17 is rotatably mounted on a shaft 18 that is also suspended between beams 15. Conveyor 11 in moving between drum l4 and pulleys 13 is wrapped around a portion of the surface of drum 17. Conveyor 10 is mounted on drum 7, pulleys l9, and a conveyor bowing support 20. Pulleys 19 and support 20 are both rotatably mounted on frame 3. The belts of conveyor 10 are preferably interleaved on drum 7 with the belts of conveyor 1. Conveyor 10 is also wrapped around a portion of drum 17. Thus, drum 17 serves to change the movement of stream 2 as it is transported between conveyors l0 and 1 1 from a horizontal direction to a vertical direction. Conveyor 10 is the inner conveyor and conveyor '11 is the outer conveyor. A spur gear is attached to shaft 8 and a spur gear 26 is attached to shaft 21. Spur gears 25 and 26 mesh. As conveyor 1 is driven in a clockwise direction by the printing press, conveyors l0 and 11 are also driven in a clockwise direction at the same translational speed as conveyor 1 because conveyor 10 is wrapped around drum 7 and conveyor 11 is coupled to drum 7 through spur gears 25 and 26. Drum 17, which is freely rotatable, turns as conveyors l0 and 11 pass across its surface. In summary, the signature transporting elements of the machine of FIG. 1 are all driven by the printing press and synchronized to its operation. As the speed of the printing press increases, the speed of conveyor 1 and conveyors 10 and 11 experiences a corresponding increase. The simplicity of design of this arrangementallows it to turn relatively freely and permits it to be easily driven by the press.

The radius of drum 17 is the same order of magnitude or larger than the length of the signatures of stream 2. It has been found that when this relationship is satisfied most of the air trapped between the sheets of the signatures as they come off the printing press is squeezed from them while they are wrapped around drum 17 by conveyors l0 and 11. Further, the radius of curvature of the signatures when they are wrapped around drum 17 is then large enough to prevent destruction of the pin hole connections of the signatures, thereby keeping the signatures intact. Consequently, the signatures may be run through the machine with any desired orientation of the folded edge-leading, trailing, or sideways. Speed adjustment for conveyor 11 is also not necessary when the thickness of the signatures is varied because the large radius of drum 17 makes the difference in tangential velocity of conveyors l0 and 11 where they are wrapped around drum l7 inconsequential.

Stream 2 is carried by conveyor 1 to conveyor 10. From there it travels between conveyors 10 and 11 until it reaches a point short of the front side of stack 6 where support 20 is located. Conveyor 11 extends upward beyond support 20, car- 'rying with it the signatures of stream 2 which are pushed against the end of stack 6. Each signature in turn is moved into alignment along the bottom horizontal surfaces of a pair of stops 28. Stops 28 are mounted on rod 16.

As illustrated in FIG. 2, support 20 comprises rotatable drums 29 and 30 disposed in a V-shaped arrangement. Drum 29 is rotatably supported between brackets 31 and 32, and drum 30 is rotatably supported between brackets 32 and 33. Pulleys 13 are mounted on rod 16 so they are staggered and press the belts of conveyor 11 against support 20. Thus, conveyors l0 and 11 both conform to the V-shape of support 20, beginning to bow in their cross sections when they leave drum 17 for receiver 5, and the signatures in stream 2 are stiffened by conveyors l0 and 11 before the signatures reach stack 6. Each signature is substantially bowed along its entire length toward stack 6 to stiffen it as it slides across the end of stack 6 and up against stops 28. This increased rigidity that is achieved discourages mutilation of the signatures and, therefore, promotes trouble-free, efficient operation of the machine irrespective of which edge, folded or unfolded, is leading.

Pulleys 13 are displaced downward from the backside of stack 6 sufficiently so that conveyor 11 extends across only a portion of the end of stack 6 to a point short of the backside. The downward displacement preferably equals the amount of offset of the overlapping signatures in stream 6, i.e., the distance between the leading edges of successive signatures in stream 2. Consequently, as the top surface of each signature in turn near its leading edge approaches stops 28, it gradually moves out of contact with conveyor 11 until the leading edge abuts against stops 28, at which point the surface of the signature is completely out of contact with conveyor 11, because the following signature in stream 2 is interposed therebetween. Thus, the signatures of stream 2 are only pushed by conveyor 11 as long as they are capable of moving. As soon as stops 28 prevent further movement of a signature, conveyor 11 moves out of contact with such signature. This prevents the bottom, unfolded edges of the signatures from being peeled up toward stops 28 by conveyor 11.

Receiver 5 comprises a flat horizontal platform 40 and independently movable vertical posts 41. Platform 40 has slots 43 4 (FIG. 2) in which endless belts 4'4travel at the level of the surplatform 40 by means not shown. Because of belt 48, belt 44 is driven in a clockwise direction by conveyor 1, but at a much slower translational speed than conveyor '1 due to the large size of pulleys 46 relative to drum 7. If desired, a commercially available gearing arrangement having a variable gear ratio could be interposed between belt 48 and shaft 47 so that the relative speed of belt 44 can be adjusted to accommodate different thicknesses of signatures. As each signature of stream 2 is in turn pushed up in alignment along stops 28, stack 6 is urged to the'right as'viewed in FIG. 1, and belts 44 carry stack 6 to the right at thesame speed the signatures are movedinto alignment. Thus, stack 6 is carried along platform 40 by'belts 44 rather than sliding.

' Posts 41 are rotatably mounted on rods 52 that extend through longitudinal slots 51 inplatform 40'to bases 50 (FIG. 4). Bases 50 ride back and forth along the length ofplatform 40 on cylindrical rails 53 that are mounted under platform 40. Weights 60 are connected'bycables 61 to bases 50. Cables 61 ride on pulleys 62 rotatably mountedunder platform 40. The

force of gravity on weights60 urges posts against the end of stack 6 in receiver 5. ln case'the length of stack-6 on the backside and front side are not the same, posts '41 adjust themselves accordingly so they arev both urged firmly against the end of stack 6=to provide good support therefor. To remove a portion of stack 6 i.e., a lift, the operator of the machine must only grasp'the desired signatures'with one hand and pull them out of stack 6 in a horizontal direction transverse to the length of stack 6, represented in FIG. 2 by an arrow 27QWhile the signatures are being pulled out of stack 6, they roll over the surface of posts 41 and 41 return in succession. This allows the operator to operate the machine without touching or handling any other materials or equipment than the signatures he is removing, eliminating all extraneous motions and effort and permitting operation at fastest pres's speeds.

A marking pencil or crayon 63 is mounted on top of platform A spring biased, pivotable arm 64 mounted on the end of drum l7 extendsslightly beyond its circular perimeter where arm 64 engages a microswitch 65 once each revolution of drum -17. Each time microswitch 65 is energized by arm 64 a solenoid is momentarily actuated and marking pencil 63 is pushed against stack 6 to make a mark thereon. Thus, the signatures are periodically marked in synchronism with the movement of conveyors 1, l0, and 11, as well as with the printing press. Many other variations for marking the signatures in synchronism with the movement of the printing press either directly or indirectly could be employed. For example, marking pencil 63 could be mounted'directly on drum -17 or on an arm moved'by a cam on drum 17 so it marks signatures each time it rotates without a solenoid. 0r solenoid'66 could be controlled responsive to the operation of a signature counter associated with the printing press.

"Pulleysl9 are rotatably mounted on shafts 70'FlG. 3). A Rod 71 is attachedto frame 3.Pairs of rods 72 and 73, which are attached touch of shafts 70, pass through openings in rod 71. Tension springs 74 and 75 are disposed around rods 72 and 73, respectively, on the opposite side of rod 7] from pulleys 19. Springs 74 and 75 are retained between the surface of rod "and bolts 76 and 77 that terminate rods 72 and 73, respectively. Whenever the signatures of stream 2 passing between conveyors l0 and I1 experience an increase in thickness, one or more of pulleys 19 are pulled upward and to the'left, as viewed in FIG. 1, to compress springs 74 and 75 and to increase thelengthof'conveyor between drum 7 and support 20. Thus, changes in thickness of the signatures of stream 2 are compensated for by pulleys 19 so conveyor 10 always remains firmly in contact with stream 2 without pressing too tightly against it or becoming too slack.

For the purposes of simplicity, no flanges are shown in the drawings on the pulleys and drums on which the belts are mounted. In practice, flanges or other means to prevent the belts from moving laterally would be provided.

lclaim:

l. A machine for arranging in an aligned stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping the bottom surface of the following sheet, the machine comprising:

areceiver adapted to support the aligned stack of sheets; first and second adjacent conveyors adapted to transport between them the stream of sheets to the receiver such that the stream approaches one end of the stack in a directiontransverse to its length and the bottom surfaces of the sheets face toward the one end of the stack, the first conveyor being in contact with the trailingedges of the sheets and the second conveyor being in contact with the leading edges of the sheets;

the first conveyor extending to a first point short of the front side of the stack;

the second conveyor extending across the end of the stack to push each sheet in turn into alignment in the stack;

the first and second conveyors being bowed across their width at the first point of the front side of the stack to stiffen the sheets inthe stream before they reach the stack, the firstand second conveyors being bowed at their cen-' ters toward the one end of the stack; and

a stop disposed along the backside of the stack transverse to the stream approaching the stack so as to align the sheets.

2. The machine of claim 1, in which the first and second conveyorsare endless belt arrangements mounted on rotatablesupports, andlone of the supports for the first conveyor is located at the first point andis'bowedat its center away from the second conveyor.

'3. The machine of claim 2, in which the belt arrangement of the'first conveyor comprises a pluralityof endless belts sideby-side and the onesupport for the first conveyor comprises two drums arranged in a V-shape.

4.'The machineof claim 1, in which a direction changing rotatably supported drum is provided around which the conveyors are partially wrapped as they transport the stream of sheets to the receiver, the drum having a radius that is at least the same order of magnitude as the length of thesheets.

5. The machine of claim 4, in which the outer-conveyor wrapped aroundthe drum comprises an endless belt arrangement mounted on at least threeaxially spaced apart, rotatable supports, the two supports between'which the belt arrangement passes across-the drum being translationally fixed and the third support being movable transverse to its axis of rotation to permit the length of belt between the two-supportszto change responsive to changes in the thickness of thesheets.

'6. The machine of claim 1, in which the receiver is a horizontal platform that has two elongated independently movable rotatable vertical members located-at the other-end of the stack from the conveyors and the members are loaded such that they are urged against the other end of the stack as the sheets in the .stack move away from the conveyors.

7. The-machine of claim 1, in which means synchronized to the movement of the conveyors periodically markthe sheets,

such as signatures, that are movingedgewisc in a stream with thetop surface of each sheet overlapping the bottom surface of the following sheet, the system comprising:

a stream of flexible sheets moving edgewise;

a receiver adapted to support an aligned stack of sheets;

first and second adjacent conveyors adaptedto transport between them the stream of sheets to the receiver such that the stream approaches one end of the stack in a direction transverse to its length and the bottom surfaces of the-sheets face toward the one end of the stack, the first conveyor being in contact with the trailing edges of the stream of sheets and the second conveyor being in contact with the leading edges of the stream of sheets;

the first conveyor extending to a first point short of the front side of the stack; a

the second conveyor extending across a portion of the end of the stack to a second point short of the backside of the stack so the second conveyor gradually moves out of contact with each sheet as it moves into alignment in the stack, the second point being spaced from the backside of the stack by the amount of offset of the sheets in the overlapping stream; and v a stopdisposed along the backside of the stack transverse to the stream approaching the stack so as to maintain alignment of the sheets.

i 10. A machine for arranging in an-aligned horizontal stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping the bottom surface of thefollowing sheet, the machine comprismg:

a horizontal platform adapted to support the aligned stack of sheets;

a stop disposed along the backside of thestack at one end thereof to align the sheets on the backside of the stack;

means for transporting the stream of sheets to the platform such that the stream approaches the one end of the stack in a vertical direction with the bottom surfaces of the sheets facing toward the one end of the stack and each sheet in turn moves up against the stop into horizontal alignment to push the other end of the stack horizontally; and

first and second individually movable, elongated vertical members located at the other end of the stack, the members'being loaded such that they are urged individually against the otherend of the stack as it is pushed by the sheets moving into horizontal alignment from the stream.

11. The machine of claim 10, in which the elongated vertical members are adapted to slide across the platform in a direction parallel to the length of the stack and are loaded by weights suspended by cables attached to the respective members,.the weights being lifted as the members slide away from the one end of the stack. 1

12. A machine for arranging in an aligned stack, flexible sheets, such assignatures, that are moving edg'ewise in a stream with the top surface of each sheet overlapping the bottom surface of the following sheets, the machine comprising: a receiver adapted to support the aligned stack of sheets; a stop located-along the backside of the stack at .one end thereof to align the sheets on the backside of the stack; means for transporting the stream of sheets to the receiver such that the stream approaches the one end of the stack 7 in a direction transverse toits length with the bottom surfaces of the sheets facing toward the one end of the stack and each sheet in turn moves up against the stop into horizontal alignment to push the other end of the stack; releasable means for supporting the other end of the stack;

and Y 7 means synchronized to the transporting means for periodically making visible marks on the sheets at points that are visible when the sheets are arranged in the stack on the receiver, thereby producing along the length of the stack a visible indication of the number of sheets in the stack. 13. The machine of claim 12, in which the transporting means comprises first and second adjacent conveyors, the first conveyor is in contact with the trailing edges of the sheets, the second conveyor is in contact with the leading edges of the sheets, the first conveyor extends to a point short of the front side of the stack, the second conveyor extends across the one end of the stack to push each sheet in turn into alignment in the stack, a direction changing rotatablyv supported drum is provided around which the conveyors are wrapped as they transport the stream of sheets to the receiver, the marking means is mounted on the receiver to come into contact with the stream of sheets once each drum rotation.

14. The machine of claim 12, in which the marking means is a marking pencil mounted on the receiver to contact the stream of sheets once each revolution of the drum.

15. The machine of claim 10, in which the vertical members are rotatable and cylindrical.

16. The machine of claim 12, in which the releasable means for supporting the other end of the stack comprises two elonloaded such that they are urged against the other end of the stack. 

1. A machine for arranging in an aligned stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping The bottom surface of the following sheet, the machine comprising: a receiver adapted to support the aligned stack of sheets; first and second adjacent conveyors adapted to transport between them the stream of sheets to the receiver such that the stream approaches one end of the stack in a direction transverse to its length and the bottom surfaces of the sheets face toward the one end of the stack, the first conveyor being in contact with the trailing edges of the sheets and the second conveyor being in contact with the leading edges of the sheets; the first conveyor extending to a first point short of the front side of the stack; the second conveyor extending across the end of the stack to push each sheet in turn into alignment in the stack; the first and second conveyors being bowed across their width at the first point of the front side of the stack to stiffen the sheets in the stream before they reach the stack, the first and second conveyors being bowed at their centers toward the one end of the stack; and a stop disposed along the backside of the stack transverse to the stream approaching the stack so as to align the sheets.
 2. The machine of claim 1, in which the first and second conveyors are endless belt arrangements mounted on rotatable supports, and one of the supports for the first conveyor is located at the first point and is bowed at its center away from the second conveyor.
 3. The machine of claim 2, in which the belt arrangement of the first conveyor comprises a plurality of endless belts side-by-side and the one support for the first conveyor comprises two drums arranged in a V-shape.
 4. The machine of claim 1, in which a 90* direction changing rotatably supported drum is provided around which the conveyors are partially wrapped as they transport the stream of sheets to the receiver, the drum having a radius that is at least the same order of magnitude as the length of the sheets.
 5. The machine of claim 4, in which the outer conveyor wrapped around the drum comprises an endless belt arrangement mounted on at least three axially spaced apart, rotatable supports, the two supports between which the belt arrangement passes across the drum being translationally fixed and the third support being movable transverse to its axis of rotation to permit the length of belt between the two supports to change responsive to changes in the thickness of the sheets.
 6. The machine of claim 1, in which the receiver is a horizontal platform that has two elongated independently movable rotatable vertical members located at the other end of the stack from the conveyors and the members are loaded such that they are urged against the other end of the stack as the sheets in the stack move away from the conveyors.
 7. The machine of claim 1, in which means synchronized to the movement of the conveyors periodically mark the sheets, thereby producing along the length of the stack an indication of the number of sheets in the stack.
 8. The machine of claim 1, in which the second conveyor extends across only a portion of the end of the stack to a second point short of the backside of the stack so the second conveyor gradually moves out of contact with each sheet as it moves into alignment in the stack.
 9. A system for arranging in an aligned stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping the bottom surface of the following sheet, the system comprising: a stream of flexible sheets moving edgewise; a receiver adapted to support an aligned stack of sheets; first and second adjacent conveyors adapted to transport between them the stream of sheets to the receiver such that the stream approaches one end of the stack in a direction transverse to its length and the bottom surfaces of the sheets face toward the one end of the stack, the first conveyor being in contact with the trailing edges of the stream of sheets and the second cOnveyor being in contact with the leading edges of the stream of sheets; the first conveyor extending to a first point short of the front side of the stack; the second conveyor extending across a portion of the end of the stack to a second point short of the backside of the stack so the second conveyor gradually moves out of contact with each sheet as it moves into alignment in the stack, the second point being spaced from the backside of the stack by the amount of offset of the sheets in the overlapping stream; and a stop disposed along the backside of the stack transverse to the stream approaching the stack so as to maintain alignment of the sheets.
 10. A machine for arranging in an aligned horizontal stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping the bottom surface of the following sheet, the machine comprising: a horizontal platform adapted to support the aligned stack of sheets; a stop disposed along the backside of the stack at one end thereof to align the sheets on the backside of the stack; means for transporting the stream of sheets to the platform such that the stream approaches the one end of the stack in a vertical direction with the bottom surfaces of the sheets facing toward the one end of the stack and each sheet in turn moves up against the stop into horizontal alignment to push the other end of the stack horizontally; and first and second individually movable, elongated vertical members located at the other end of the stack, the members being loaded such that they are urged individually against the other end of the stack as it is pushed by the sheets moving into horizontal alignment from the stream.
 11. The machine of claim 10, in which the elongated vertical members are adapted to slide across the platform in a direction parallel to the length of the stack and are loaded by weights suspended by cables attached to the respective members, the weights being lifted as the members slide away from the one end of the stack.
 12. A machine for arranging in an aligned stack, flexible sheets, such as signatures, that are moving edgewise in a stream with the top surface of each sheet overlapping the bottom surface of the following sheets, the machine comprising: a receiver adapted to support the aligned stack of sheets; a stop located along the backside of the stack at one end thereof to align the sheets on the backside of the stack; means for transporting the stream of sheets to the receiver such that the stream approaches the one end of the stack in a direction transverse to its length with the bottom surfaces of the sheets facing toward the one end of the stack and each sheet in turn moves up against the stop into horizontal alignment to push the other end of the stack; releasable means for supporting the other end of the stack; and means synchronized to the transporting means for periodically making visible marks on the sheets at points that are visible when the sheets are arranged in the stack on the receiver, thereby producing along the length of the stack a visible indication of the number of sheets in the stack.
 13. The machine of claim 12, in which the transporting means comprises first and second adjacent conveyors, the first conveyor is in contact with the trailing edges of the sheets, the second conveyor is in contact with the leading edges of the sheets, the first conveyor extends to a point short of the front side of the stack, the second conveyor extends across the one end of the stack to push each sheet in turn into alignment in the stack, a direction changing rotatably supported drum is provided around which the conveyors are wrapped as they transport the stream of sheets to the receiver, the marking means is mounted on the receiver to come into contact with the stream of sheets once each drum rotation.
 14. The machine of claim 12, in which the marking means is a marking pencil mounted on the receiver to contact the stream of sheets once each revolution of the drum.
 15. The machine of claim 10, in which the vertical members are rotatable and cylindrical.
 16. The machine of claim 12, in which the releasable means for supporting the other end of the stack comprises two elongated, independently movable, vertical members located at the other end of the stack on the receiver, the members being loaded such that they are urged against the other end of the stack. 